Arc chute having cooling and deionizing elements arranged at the exhaust end



Aug. 2, 1960 v. A. MoRTENscN ET AL 2,947,339

` ARC CHUT E HAVING COOLING AND DEIONIZING ELEMENTS ARRANGED AT THE EXHAUST END Filed Feb 28, 1957 2 Sheets-Sheet 1 gwada/brio Uu/bon @Worth/mmm mma/( 5. afk/altem Aug. 2, 1960 v. A. MoRTENsoN ETAL 2,947,839

ARC CHUTE HAVING COOLING AND DEIoNIzING ELEMENTS ARRANGED AT THE EXHAUST END Filed Feb. 28, 1957 2 Sheets-Sheet 2 ff/@viii f/ff lI Il ll (l, l`` Il I I Il I /vvUAZ/vlkorlo @Ji/:kon da. @Houma/.wn

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ARC CHUTE HAVING COOLING AND DEIONIZ- ING ELEMENTS ARRANGED AT THE EXHAUST END Victor A. Mortenson, Scituate, Donald E. Weston, Brookline, and Martin J.'Reilly, South Weymouth, Mass., asslgnors to Allis-Chalmers Manufacturing Company, Milwaukee Wis.

Filed Feb. 28, 1957, Ser. No. 643,038

2 Claims. (Cl. 200-147) This invention relates to circuit interrupting devices and more particularly to means for reducing the amount of ionized gas discharge above the arc chute of a circuit breaker structure.

In the construction and operation of circuit breaker structures, it is frequently necessary to provide means t or extinguishing quickly the arc which is drawn between separable arcing contacts. This arc is usually blown by blowout means, such as a magnetic blowout coil or an air blast, into an arc chute which is arranged to quench the arc by lengthening it, `cooling it, or a combination of both.

Arc chutes having spaced insulating plates to lengthen the arc or squeeze the arc into narrow slots have been used to rapidly increase the arc voltage, decrease the arc current and greatly improve the power factor, thereby facilitating interruption of the arc at a natural or forced current zero. However, it has been found in many cases that the arc voltage developed by the arc chute was not the most favorable for interrupting the power circuit.

The geometry of the arc chute determines the arc voltage which will be developed for circuit interrupting purposes. This arc voltage can be expressed as a percentage of the line voltage and, therefore, is not limited to any particular voltage class of breaker. The arc chute for an electromagnetic type of circuit breaker is designed to perform two functions, namely, to interrupt a power `circuit and to enclose the arc products. As a circuit interrupting device the arc chute of the magnetic breaker must be capable of controlling the arc voltage, the arc current, the arc energy, the rate of rise of recovery voltage and the phase relationship between arc current and line voltage at the instant of interruption. As an enclosing structure for cooling and deionizing the arcing products, the arc chute of the magnetic breaker must protect all the surrounding operating parts Ifrom .the effects of the arc or the arc products. All of the gases exhausted from the arc chute must be rendered harmless before being exposed to any of the surrounding circuit breaker structure or allied equipment. many cases, however, the gases exhausted from the arc chute remained ionized and caused a visible discharge such as ame emission, at the exhaust end of the arc chute structure.

Therefore, in accordance with the invention claimed, a new and improved arc interrupting device is provided which cools the gases exhausted from the interrupting device within the arc chute enclosure before final discharge of the gases to atmosphere, thereby eliminating or substantially reducing ionized gas discharge or ame emission from above the arc chute of the interrupting device. The arc chute comprises a plurality of spaced insulating plates arranged to extend longitudinally of the axis of the arc chute `at the arc receiving end thereof and a plurality of isolated groups of spaced tubular cooling elements arranged at the exhaust end of the arc chute. The cooling elements are spaced downstream from the insulating plates and each of the groups of cooling elef' s 1C@ 2 ments may lbe insulatingly separated vfrom each of the other groups of elements.

It is, therefore, one object of the present invention to provide a new 4and improved arc interrupting device in which reduction of ionization and visible discharge at the exhaust end of the arc chute is accomplished by cooling the arc products and gases within the arc chute enclosure before discharge to atmosphere.

Another object of this invention is to provide a new and improved arc interrupting device in which arc discharge cooling means function lto cool the arc products and gases without otiering a pneumatic impedance to their iiow.

A further object of this invention is to provide a new and improved -arc interrupting device in which cooling elements are arranged in a predetermined manner in the exhaust end of of an arc chute structure to reduce ionization and visible discharge therefrom.

A still further object of this invention is to provide a new and improved arc interrupting device in which arc discharge cooling means arranged at the exhaust end of the arc chute are arranged in groups insulatingly separated from each other.

A still further object-of this invention is to provide a new and improved arc interrupting device in which arc discharge cooling means are detachably `arranged within the exhaust end of the arc chute structure.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. l is a view in cross section of a magnetic blowout type circuit breaker employing the present invention;

Fig. 2 is a plan view of the arc chute structure of the circuit breaker illustrated in Fig. l; and

Fig. 3 is a sectional view of the arc chute illustrated in Fig. l taken along the line III-Ill and embodying the invention.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs 6 and 7 for connecting the circuit breaker to line conductors (not shown). Although in general, `circuit breakers of the type considered in Fig. l are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawingsY and the circuit -breaker will be described in detail as if.'

it was of the single pole type.

The circuit interrupter or -breaker in Fig. l comprises essentially means `for opening the circuit -to form the interrupting arc and an arc extinguishing structure. Spe-` ciiically, the circuit opening means comprises a lixed current carrying contact 8, a tertiary contact 9, a fixed arc- 'ing contact 10, and a movable arcing contact 11. Arcing contact 11 is mounted on `a lever 12 which is pivotally mounted at 13 on an extension 14 of the circuit breaker stud 6 and is operated by means of a reciprocally movable rod 15. The operating rod 15 is suitably connected to an actuating mechanism (not shown) for operating the movable contact between closed and open circuit positions. Fig. l illustrates the movable contact 11 in closed position. The arcing contacts are electrically connected to the lower ends of terminal studs 6 and 7. Accordingly, when the breaker is connected in series in a power circuit and the arcing contacts are separated, an arc may be initiated across the gap formed between the contacts.

For interrupting this power arc, an arc extinguishing structure, such as an arc chute 16, may be mounted so as to receive the power arc which is under the inuence of the magnetic blowout means. ably is disposed directly about and above the arcing contacts, as shown, when the blowout means act upward, but may be mounted in any other suitable location when the blowout means act in other directions. The switch or arcing contacts and the magnetic blowout structure can assume any preferred form so. that a brief description thereof will be sucient. The magnetic blowout means may comprise a core 17, poles 18 and a coil 19 which is electrically connected to the terminal stud 7 and tol aV metallic are runner 20 so that the arc current (as the arc travels along the runner) ows through the blowout coil in a manner well known in the art.

Normally the currentA is carried in the closed circuit position of the breaker by. the spring biased contact 8. As the movable arcing Contact 11 is actuated to open circuit position, current is shunted from ixed contact 8 first to fixed Contact 9 and afterwards to xed arcing contact 10. As the arc is drawn by thermovable arcing contact 11, the arc terminal of arcing contacts 10 is transferred to arc runner 20, which is usually an extension arm of the ixed arcing contact 10. As the movable arcing contact 11 approaches or reaches its full opening stroke the arc terminal transfers from the movable arcing Icontact 11 to an arc runner 21 which directs the arc in the arc chute 16. The arcing contact 10 and the arc runner 2i) are electrically connected in series with the blowout coil 19 and stud 7. Accordingly, the blowout coil is already energized at the inception of the arc to influence -the arc in la well known manner, i.e. to drive it in the arc chute 16 in an expanding loop. It will be apparent to one skilled in the art that the blowout field can be utilized in the most eiiicient manner by disposing the iron poles 18 so as to cooperate with the blowout coil in the conventional manner outside of the arc chute.

Arc chute 16 is provided with a plurality of slotted spaced insulating barrier plates 22 arranged to extend longitudinally of the axis of the arc chute. If desired these barrier plates may be arranged in groups with each group comprising a plurality of types of barrier plates having different geometrical configurations. As shown in Fig. 3 the slots 23 of barrier plates 22 are aligned at theirupstream end adjacent the zone of arc initiation to form an arc passage. As is well known in the art the slots 23-may be arranged in staggered relation at their downstream ends. This out of registryl or staggered relationship of slots 23- causes the formation of a zigzag shaped arc path. Barrier plates 22 may be provided in some applications of this invention with a plurality of apertures or perforations 24 arranged to extend from the downstream ends of slots 23, as shown in Fig. 3, toward the exhaust end of the arc chute. Inother applications of this invention, the perforations 24 may be omitted from barrier Vplates 22.

In accordance with Ithe invention claimed a plurality of space cooling elements such as, for example, metallic, non-metallic or insulating tubes 25 are arranged within the exhaust passage-26 substantially completely across the exhaust end of the arc chute 16 above or downstream of the barrier plates 22. n Although the cooling elements are-shown as tubes it is intended to be within the scope of this invention to use any shape or form of cooling element 25. Tubes 25 are arranged in isolated groups to extend transversely to the longitudinal axis of the arc chuteand to the direction of movement of the arc, arc products and gases through the are chute structure. Each group may be separated or compartmented from the adjacent groups by insulating material Z7. The size and' number of compartments used in a particular arc chute structure is determined by the voltage gradient across the arc chute. Each group of tubes is exposed and reacts on only a portion of the voltage across the arcing contacts orV arc runners.

Compartmentization of the arc chute structure assures j that each group of tubes or cooling elements functions to The arc chute preferits'fullest capacity by cooling only a certain portion of the generated gas and arc products. The number of tubes used and their geometrical arrangement within the arc chute enclosure is determined by the amount of cooling required and the particular position and amount of discharge volume of arc products and gases from the barrier plate stack. Tubes 25 are staggered in such a manner that the space between them provides full discharge of the arc products and gases from the arc chute structure at the same time being so arranged that the arc products and gases discharged from the barrier plate stack must pass adjacent to the cooling elements 25 before being expelledto atmosphere. In this manner cooling is accomplished without restriction to the normal flow of gases or arc products.

As noted from Fig. l of the drawings the group of cooling elements arranged adjacent each end of the arc chute structure and above the arc runners 20 and 21 cornprisesa greater number of cooling elements which extend farther downstream from the arcing contacts than do the elements of .the groups arranged intermediate the ends of the arc chute structure. This arrangement provides a larger'number of cooling elements immediately above the zones of the greatest are products and gas discharge production, namely, above the area adjacent the ends of the arc chute structure and near the zones of the arc runners vthan do the groups intermediate the ends of the arc chute structure.

If so desired the respective groups of cooling elements 25 may be arranged in removable or detachable cornpartrnents which can be temporarily arranged in a given position in the arcY chute structure and later moved to another more effective position. The tubes of each compartmentlare arranged in a plurality of rows wherein each cooling element of each row is arranged in staggered relationship to the elements of'adjacent rows. At least some of the cooling elements in at least one of the groupsl may be composed of insulating material. In the removable compartment structures the walls of the compartments are made ofinsulating material of the type capable of withstanding the heat of the are products and gases.

The cooling element or compartments of cooling elements are arranged as after coolers in the exhaust end' of the arc chute structure and are spaced a predetermined' distance downstream from the barrier plates 22. TheseI elements or tubes function to cool the arc products or' gases without offering a pneumatic impedance to their flow. In other words, the performance of the barrier plate stack isnot affected by pneumatic blocking and the full are interrupting ability of the barrier plate stack is developed.

Although but one embodiment of the present inventioni has been illustrated and described, it will be apparent` to those skilled in the art that various changes and modiiications may be made therein without departing from thev spirit of the invention or from the scope of the appended claims.

What is claimed is: Y

l. An electric circuit interrupter comprising relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, Said arc chute comprising a plurality vof spaced insulating plates arranged to extend longitudinally of the axis of said chute at the arc receiving end thereof, and a plurality of groups of spaced tubular cooling elements arranged in staggered relationship in compartments downstream from said insulating plates, each of said compartments being formed of insulating material and detachably mounted at the exhaust end of said chute, said compartments isolating said groups from each other, said groups in some of said compartments comprising a greater number of said elements than said groups in the remainder of said compartments.

2. An` electric circuit interrupter comprising relatively.

l 21,947,839 T .t 5 6 movable contacts, means for drawing an arc between References Cited in the file of this patent said contacts, an arc chute for receiving the arc at one UNITED STATES PATENTS end thereof and exhausting the arc products at the other end, said arc chute comprising a plurality of spaced ins rao "gulyl g" sulating plates arranged to extend longitudinally of the 5 2310'72g Bmtlet 9 1943 axis of said chute at the arc receiving end thereof, and 949 Vruet "Dn 28 1943 a plurality of groups of spaced tubular cooling elements gom S a e Jlc' 27 1948 arranged in staggered relationship in compartments down- 26433 14 Rcfttl Juney 23 1953 stream from said insulating plates, each of said com- 2738398 T1 ey M 1 13 1956 partments being formed of insulating material and de- 10 ay or a tachably mounted at the exhaust end of said chute, said FOREIGN PATENTS compartments isolating said groups from each other, said groups in said compartments arranged adjacent each side 344,988 Great B1{ta{n Mar- 19 1931 portion of said chute comprising a greater number of said 589,270 Great Bfltayl June 16 1947 elements than said groups in said compartments arranged 15 7151121 Great Bfltam Sept- 281 1954 intermediate the side portions of said chute. 763,510 Great Britain Dec. 12, 1956 

